Tuesday, June 27, 2006

The secrets of the mind convene splendidly,Though the mind is meek.To be aware inwardlyof brain and beautyIs dark too recognizable.Thought looking out on thoughtMakes one an eye:Which it shall be, both decide.One is with the mind alone,The other is with other thoughts goneTo be seen from afar and not known.

Sunday, June 25, 2006

No, of course not. The question really is, does your precuneus make you conscious?

In The Neurocritic's last entry on hypnosis and consciousness, Faymonville et al. (in press) raised the possibility that the precuneus "...is part of the critical neural network subserving conscious experience."

So what's up with the precuneus? Where is it located, and what does it do? A recent review by Cavanna and Trimble (2006) is one place to start learning about this up-and-coming brain region.

Functional neuroimaging studies have started unravelling unexpected functional attributes for the posteromedial portion of the parietal lobe, the precuneus. This cortical area has traditionally received little attention, mainly because of its hidden location and the virtual absence of focal lesion studies. However, recent functional imaging findings in healthy subjects suggest a central role for the precuneus in a wide spectrum of highly integrated tasks, including visuo-spatial imagery, episodic memory retrieval and self-processing operations, namely first-person perspective taking and an experience of agency. Furthermore, precuneus and surrounding posteromedial areas are amongst the brain structures displaying the highest resting metabolic rates (hot spots) and are characterized by transient decreases in the tonic activity during engagement in non-self-referential goal-directed actions (default mode of brain function). Therefore, it has recently been proposed that precuneus is involved in the interwoven network of the neural correlates of self-consciousness, engaged in self-related mental representations during rest. This hypothesis is consistent with the selective hypometabolism in the posteromedial cortex reported in a wide range of altered conscious states, such as sleep, drug-induced anaesthesia and vegetative states. ... [The authors describe] preliminary evidence for a functional subdivision within the precuneus into an anterior region, involved in self-centred mental imagery strategies, and a posterior region, subserving successful episodic memory retrieval.

The precuneus seemed poised to break out into the mainstream in the mid-90's, ever since it was found to be highly active when people were remembering words from a list they had studied earlier (compared to new words they hadn't studied). At first, this activity seemed related to the use of mental imagery during retrieval (Fletcher et al., 1995), because precuneus activity increased for highly concrete and imageable word pairs (e.g., "River-Stream") but not for abstract word pairs (e.g., "Justice-Law"). Subsequent experiments, however, did not replicate this result (Krause et al., 1999).

The second big boost for precuneus fans (and the one relevant for hypnosis) came from the aforementioned "default mode" studies of Raichle and colleagues (Gusnard & Raichle, 2001). The precuneus shows shows the highest resting metabolic rate of all the regions implicated in "the resting state" (often assessed with eyes closed, when the subjects presumably have a major alpha rhythm going in their EEGs, but also evaluated during "passive viewing" conditions when people are looking at a + sign or some other image). SO the hypothesis of these investigators (as quoted in Faymonville et al., in press) is that:

the precuneus and interconnected posterior cingulate and medial prefrontal cortices are engaged in continuous information gathering and representation of the self and external world (Gusnard and Raichle, 2001).

The "self-representation" part appears to be off in autistic individuals (Kennedy et al., 2006), because they fail to "engage" the default mode network during rest, relative to an active cognitive task condition. But in the same vein as the critique of the "Lose Yourself" study, a relatively quiet precuneus don't necessarily mean you're not conscious, it can just reflect a focus on things other than yourself and your surroundings. So perhaps the precuneus and its network of friends contribute to our "self-conscious" state.

One of the most intriguing recent proposals was a speculation by Buckner and colleagues (2005), when pondering the meaning of an underactive "default mode" network in patients with Alzheimer's disease:

Alzheimer's disease (AD) and antecedent factors associated with AD were explored using amyloid imaging and unbiased measures of longitudinal atrophy in combination with reanalysis of previous metabolic and functional studies. In total, data from 764 participants were compared across five in vivo imaging methods. Convergence of effects was seen in posterior cortical regions, including posterior cingulate, retrosplenial, and lateral parietal cortex. These regions were active in default states in young adults and also showed amyloid deposition in older adults with AD. At early stages of AD progression, prominent atrophy and metabolic abnormalities emerged in these posterior cortical regions; atrophy in medial temporal regions was also observed. Event-related functional magnetic resonance imaging studies further revealed that these cortical regions are active during successful memory retrieval in young adults. One possibility is that lifetime cerebral metabolism associated with regionally specific default activity predisposes cortical regions to AD-related changes, including amyloid deposition, metabolic disruption, and atrophy. These cortical regions may be part of a network with the medial temporal lobe whose disruption contributes to memory impairment.

So basically, the idea is that an overactive self-referential default-mode network burns itself out, somehow leading to the pathological state associated with amyloid deposition, neuronal death, severe brain atrophy, and the ultimate loss of self which occurs in that dreadful disease named after Alois Alzheimer.

There is not a generally accepted definition of hypnosis. For many authors it is seen as a state of focused attention, concentration and inner absorption with a relative suspension of peripheral awareness (Laureys et al., in press).

And after writing that lengthy dissertation or grant proposal, it's time to enter a fugue state...

Yeah, OK, The Neurocritic is [probably] not hypnotizable (not even by Hypnotoad). I don't know anything about hypnosis, either, but let's take a look at the process:

Hypnosis has three main components: absorption, dissociation and suggestibility (Spiegel, 1991). Absorption is the tendency to become fully involved in a perceptual, imaginative or ideational experience. Subjects prone to this type of cognition are more highly hypnotizable than others who never fully engage in such experience (Hilgard et al., 1963). Dissociation is the mental separation of components of behavior that would ordinarily be processed together (e.g., the dream-like state of being both actor and observer when re-experiencing autobiographical memories). This may also involve a sense of involuntariness in motor functions or discontinuities in the sensations of one part of the body compared with another. Suggestibility leads to an enhanced tendency to comply with hypnotic instructions. This represents not a loss of will butrather a suspension of critical judgment because of the intense absorption of the hypnotic state.

Hmmm, "suspension of critical judgment" -- that's not gonna happen here. But what are the "neural correlates" of a hypnotic state?

The Precuneus and Conscious Experience

First off, Faymonville et al. review their PET studies comparing hypnosis to a control state. Since their hypnotic induction procedure involves asking the subjects to vividly reimagine pleasant autobiographical memories, the control state was "recalling pleasant autobiographical memories while NOT under hypnosis." Which brain areas showed greater blood flow (and presumably greater neural activity) under hypnosis than in the control state? A huge chunk of the brain: "occipital, parietal, precentral, prefrontal, and cingulate cortices." Which area showed less activity under hypnosis than alertness: the medial parietal cortex (i.e., precuneus).

This area is hypothesized to be involved in the representation (monitoring) of the world around us (Gusnard and Raichle, 2001).

Raichle and colleagues have argued for a "default mode" or "resting state" of brain function that engages a certain network of brain regions (posterior cingulate and precuneus and medial prefrontal cortex) during "rest." These regions become DEactivated when people are engaged in the typical types of cognitive tasks they're asked to do in a scanner. So it's really only a "resting state" when compared to doing, say, the Stroop task. When asked to rest and stare at a plus sign, you may engage in idle daydreaming or think about what you'll have for dinner or remember your hot date from last night or silently sing.

Anyway, Faymonville et al. mention that the precuneus is "one of the most dysfunctional brain regions in states of unconsciousness or altered consciousness such as coma, vegetative state, general anesthesia, slow wave and rapid eye movement sleep, amnesia and dementia [referernces available upon request], suggesting that it is part of the critical neural network subserving conscious experience."

Saturday, June 10, 2006

First up on the hypnosis hit parade is the article by Raz et al. (in press). The last author, Mike Posner, is a prominent cognitive psychologist who has studied the cognitive and neural mechanisms of attention for over 40 years.

The authors begin by reviewing their work on attention, and suggest this psychological construct should be considered an "organ system" with a distinctive brain anatomy from other perceptual and cognitive functions. They discuss 3 component attentional systems that occupy separate neural networks: orienting, alerting, and executive control. Furthermore, they propose that each of these networks is pharmacologically distinct:

"cholinergic systems arising in the basal forebrain play an important role in orienting; the norepinephrine (NE) system arising in the locus coeruleus of the midbrain is involved in alerting; and the anterior cingulate cortex (ACC) and lateral prefrontal cortex are target areas of the mesocortical dopamine system -- involved in executive attention."

It sounds nice, but it's hard to imagine the "one attentional system, one neurotransmitter" mapping is correct.

So how does all of this relate to hypnosis?

"...evidence relating hypnotic phenomena to attentional mechanisms is mounting (Raz et al., 2002b) and there is general accord that hypnotic phenomena implicate attention (Karlin, 1979) and relate to self-regulation (Posner and Rothbart, 1998)."

I guess we'll have to take their word for it (or else read the cited references). At any rate, the major intersection between attention and hypnosis in the research realm has been elimination of the well-known Stroop interference effect in highly hypnotizable people who are under a specific post-hypnotic suggestion to avoid reading the words (Raz et al., 2002b, 2003, 2005, 2006), which is usually considered a pretty darn automatic process.

Just to quickly demonstrate the Stroop, name the font color of the words below (don't read the words).

NOW NAME THE FONT COLOR OF THE SQUIGGLY MEANINGLESS CHARACTERS PRESENTED BELOW.

@*)$&^%!_#($+(@

...except that the symbols are *really* color words. In highly hypnotizable subjects who no longer show the Stroop effect, fMRI measures dampened activity in both the ACC (perhaps reflecting lessened susceptibility to interference) and the extrastriate visual cortex (perhaps reflecting suppressed activity related to reading).

So how does all of this relate to genetics?

Old data from the 70's (Morgan et al.) suggested that hypnotizability in monozygotic twins shows a correlation of 0.52-0.63, but only 0.08-0.18 for dizygotic twins. Since Raz, Fan, and Posner subscribe to the "one transmitter, one attentional system" hypothesis, they decided to go after dopaminergic-type genes (since DA is the "executive control" transmitter).

They examined the COMT gene, which "influences performance on prefrontal executive cognition and working memory tasks (Weinberger et al., 2001)," because the "high/low enzyme activity" polymorphism (valine/methionine) had been associated with high hypnotizability previously (Ebstein et al., 1999). But my question is why would they suggest that COMT is specific to DA?

COMT (catechol-O-methyltransferase) catalyzes the transfer of a methyl group from S-adenosylmethionine to catecholamines, including the neurotransmitters dopamine, epinephrine, and norepinephrine. This O-methylation results in one of the major degradativepathways of the catecholamine transmitters.

So basically, COMT is an enzyme that breaks down all catecholemines, not just dopamine. And both DA and NE have effects on prefrontal cortex.

The prefrontal cortex guides behaviors, thoughts, and feelings using representational knowledge, i.e., working memory. These fundamental cognitive abilities subserve the so-called executive functions: the ability to inhibit inappropriate behaviors and thoughts, regulate our attention, monitor our actions, and plan and organize for the future. Neuropsychological and imaging studies indicate that these prefrontal cortex functions are weaker in patients with attention-deficit/hyperactivity disorder and contribute substantially to attention deficit/hyperactivity disorder symptomology. Research in animals indicates that the prefrontal cortex is very sensitive to its neurochemical environment and that small changes in catecholamine modulation of prefrontal cortex cells can have profound effects on the ability of the prefrontal cortex to guide behavior. Optimal levels of norepinephrine acting at postsynaptic α-2A-adrenoceptors and dopamine acting at D1 receptors are essential to prefrontal cortex function. Blockade of norepinephrine α-2-adrenoceptors in prefrontal cortex markedly impairs prefrontal cortex function and mimics most of the symptoms of attention-deficit/hyperactivity disorder, including impulsivity and locomotor hyperactivity. Conversely, stimulation of α-2-adrenoceptors in prefrontal cortex strengthens prefrontal cortex regulation of behavior and reduces distractibility. Most effective treatments for attention-deficit/hyperactivity disorder facilitate catecholamine transmission and likely have their therapeutic actions by optimizing catecholamine actions in prefrontal cortex.

Nonetheless, the overall finding on suggestion and Stroop is interesting, even if the genetics at this point are questionable.

CONTEXT: A characteristic feature of borderline personality disorder (BPD) is self-injurious behavior in conjunction with stress-induced reduction of pain perception. Reduced pain sensitivity has been experimentally confirmed in patients with BPD, but the neural correlates of antinociceptive mechanisms in BPD are unknown. We predicted that heat stimuli in patients with BPD would activate brain areas concerned with cognitive and emotional evaluation of pain. OBJECTIVE: To assess the psychophysical properties and neural correlates of altered pain processing in patients with BPD. DESIGN: Case-control study. SETTING: A university hospital. PARTICIPANTS: Twelve women with BPD and self-injurious behavior and 12 age-matched control subjects. INTERVENTIONS: Psychophysical assessment and blood oxygen level-dependent functional magnetic resonance imaging during heat stimulation with fixed-temperature heat stimuli and individual-temperature stimuli adjusted for equal subjective pain in all the participants. Main Outcome Measure Blood oxygen level-dependent functional magnetic resonance imaging signal changes during heat pain stimulation. RESULTS: Patients with BPD had higher pain thresholds and smaller overall volumes of activity than controls in response to identical heat stimuli. When the stimulus temperature was individually adjusted for equal subjective pain level, overall volumes of activity were similar, although regional patterns differed significantly. Patient response was greater in the dorsolateral prefrontal cortex and smaller in the posterior parietal cortex. Pain also produced neural deactivation in the perigenual anterior cingulate gyrus and the amygdala in patients with BPD. CONCLUSION: The interaction between increased pain-induced response in the dorsolateral prefrontal cortex and deactivation in the anterior cingulate and the amygdala is associated with an antinociceptive mechanism in patients with BPD.

Do borderline patients injure themselves to "feel" (or "feel more normal") OR to down-regulate the emotional components of pain? The results don't really answer this question or the question posed in my title, but the authors give 2 options:

Limbic deactivation has been found to correlate with the degree of coping in aversive situations in general. . . . Thus, in view of these findings, self-inflicted pain may function to normalize neural activity in specific brain regions involved in emotional and cognitive processing. Alternatively, repeated self-injury could lead to an adaptation of pain thresholds and pain processing reflected in the current findings of elevated pain thresholds and disturbed prefrontal and limbic pain processing.

Now back to road rage (aka Intermittent Explosive Disorder). Dr. Emil Coccaro, that study's co-author and chair of Psychiatry at the University of Chicago, thinks all those angry drivers stuck in traffic should just take Prozac (not public transit).

Don't push me, cause I'm close to the edgeI'm trying not to lose my headIt's like a jungle sometimes, it makes me wonderHow I keep from going under

Thursday, June 08, 2006

Omni Brain links to a new feature at Nature: a 3 month trial period of "open" peer review. For those who opt to submit their papers under this track,

authors can choose to have their submissions posted on a preprint server for open comments, in parallel with the conventional peer review process. Anyone in the field may then post comments, provided they are prepared to identify themselves. Once the usual confidential peer review process is complete, the public 'open peer review' process will be closed. Nature will report on the results after the trial period is over.

In other words, The Neurocritic must be identified by name to post open comments on the web, but may maintain anonymity if the editors send me a manuscript for review. In addition, the trial

will continue in parallel with Nature's usual procedures, and does not affect the likelihood of eventual publication of the submitted work.

So what do the editors and authors do with the open peer review comments??

Comments will be reviewed by staff before being published. You can be as critical or controversial as you like, but please don't get personal or offensive, and do keep it brief. Excessively long entries may be cropped. Remember this is for feedback and discussion - not for publishing papers or press releases.

We strongly encourage you to use your real, full name. Email addresses are required: this is just in case we need to discuss your comment with you privately. They won’t be published.

UPDATE: well, they did allow this post to get in (perhaps to demonstrate the benefits of the current peer review system):

I am the biggest name in the world in electromagnetic theory. All my attempts to publish on electromagnetic theory have for thirty years been rejected worldwide by the system of peer review.My comments are athttp://www.electromagnetism.demon.co.uk/66.htmandhttp://www.electromagnetism.demon.co.uk/67.htmIvor Catt

The neural mechanisms underlying hypnosis and especially the modulation of pain perception by hypnosis remain obscure. Using PET we first described the distribution of regional cerebral blood flow during the hypnotic state. Hypnosis relied on revivification of pleasant autobiographical memories and was compared to imaging autobiographical material in "normal alertness". The hypnotic state was related to the activation of a widespread set of cortical areas involving occipital, parietal, precentral, premotor, and ventrolateral prefrontal and anterior cingulate cortices. This pattern of activation shares some similarities with mental imagery, from which it mainly differs by the relative deactivation of precuneus. Second, we looked at the anti-nociceptive effects of hypnosis. Compared to the resting state, hypnosis reduced pain perception by approximately 50%. The hypnosis-induced reduction of affective and sensory responses to noxious thermal stimulation were modulated by the activity in the midcingulate cortex (area 24a′). Finally, we assessed changes in cerebral functional connectivity related to hypnosis. Compared to normal alertness (i.e., rest and mental imagery), the hypnotic state, significantly enhanced the functional modulation between midcingulate cortex and a large neural network involved in sensory, affective, cognitive and behavioral aspects of nociception. These findings show that not only pharmacological but also psychological strategies for pain control can modulate the cerebral network involved in noxious perception.

In the aftermath of the human genome project, genotyping is fast becoming an affordable and technologically viable complement to phenotyping. Whereas attempts to characterize hypnotic responsiveness have been largely phenomenological, data emanating from exploratory genetic data may offer supplementary insights into the genetic bases of hypnotizability. We outline our genetic and neuroimaging findings and discuss potential implications to top–down control systems. These results may explain individual differences in hypnotizability and propose new ideas for studying the influence of suggestion on neural systems.

Learning in trance: Functional brain imaging studies and neuropsychology In Press, Corrected Proof, Available online 5 June 2006 Ulrike HalsbandSummaryPlus | Full Text + Links | PDF (1080 K)This study examined the fundamental question, whether verbal memory processing in hypnosis and in the waking state is mediated by a common neural system or by distinct cortical areas. Seven right-handed volunteers (25.4 years, sd 3.1) with high-hypnotic susceptibility scores were PET-scanned while encoding/retrieving word associations either in hypnosis or in the waking state. Word-pairs were visually presented and highly imaginable, but not semantically related (e.g. monkey-street). The presentation of pseudo-words served as a reference condition. An emission scan was recorded after each intravenous administration of O-15 water. Encoding under hypnosis was associated with more pronounced bilateral activations in the occipital cortex and the prefrontal areas as compared to learning in the waking state. During memory retrieval of word-pairs which had been previously learned under hypnosis, activations were found in the occipital lobe and the cerebellum. Under both experimental conditions precuneus and prefrontal cortex showed a consistent bilateral activation which was most distinct when the learning had taken place under hypnosis.

In order to further analyze the effect of hypnosis on imagery-mediated learning, we administered sets of high-imagery word-pairs and sets of abstract words. In the first experimental condition word-pair associations were presented visually. In the second condition it was found that highly hypnotisable persons recalled significantly more high-imagery words under hypnosis as compared to low-hypnotisables both in the visual and auditory modality. Furthermore, high-imagery words were also better recalled by the highly hypnotisable subjects during the non-hypnotic condition. The memory effect was consistently present under both, immediate and delayed recall conditions. Taken together, the findings advance our understanding of the neural representation that underlies hypnosis and the neuropsychological correlates of hypnotic susceptibility.

And I gotta say - I’m going to go out on the limb here - I believe slavery was wrong. No, I don’t care who that upsets. I just hope the mainstream media give me the credit for the courage it took to say that today. I know the blogosphere is just going to explode tomorrow. But enough about me - if there can be enough about me.

No, Stephen, there can't possibly be enough about you...

So we must build walls. A wall obviously across the entire southern border. That’s the answer. That may not be enough -- maybe a moat in front of it, or a fire-pit. Maybe a flaming moat, filled with fire-proof crocodiles. And we should probably wall off the northern border as well. Keep those Canadians with their socialized medicine and their skunky beer out. And because immigrants can swim, we’ll probably want to wall off the coasts as well. And while we’re at it, we need to put up a dome, in case they have catapults. And we’ll punch some holes in it so we can breathe. Breathe free. It’s time for illegal immigrants to go -- right after they finish building those walls. Yes, yes, I agree with me.

That's right, Stephen, you tell 'em.

There are so many challenges facing this next generation, and as they said earlier, you are up for these challenges. And I agree, except that I don't think you are. I don't know if you're tough enough to handle this. You are the most cuddled generation in history. I belong to the last generation that did not have to be in a car seat. You had to be in car seats. I did not have to wear a helmet when I rode my bike. You do. You have to wear helmets when you go swimming, right? In case you bump your head against the side of the pool. Oh, by the way, I should have said, my speech today may contain some peanut products.

My mother had 11 children: Jimmy, Eddie, Mary, Billy, Morgan, Tommy, Jay, Lou, Paul, Peter, Stephen. You may applaud my mother's womb. Thank you, I'll let her know. She could never protect us the way you all have been protected. She couldn't fit 11 car seats. She would just open the back of her Town & Country - stack us like cord wood: four this way, four that way. And she put crushed glass in the empty spaces to keep it steady. Then she would roll up all the windows in the winter time and light up a cigarette. When I die I will not need to be embalmed, because as a child my mother hickory-smoked me.

The White House has been kind enough to put the text of President Bush's speech advocating the "Marriage Protection Amendment" yesterday on their webpage. It would make a perfect example of illogical argumentation for a logic course.

The union of a man and woman in marriage is the most enduring and important human institution.

But apparently not so enduring that it can't withstand more people getting married.

For ages, in every culture, human beings have understood that marriage is critical to the well-being of families. And because families pass along values and shape character, marriage is also critical to the health of society. Our policies should aim to strengthen families, not undermine them.

I totally agree. But why does this claim not apply to families headed by gays? And what is the causal link between gay marriage and diminishing these good things about marriage? If gays are allowed to get married, are straight couples suddenly going to stop passing along values and shaping character?

Recommmended reading, and a depressing reminder that logic and science are not allowed by the current administration.

NOTE: Although it seemed funny and novel at the time, The Neurocritic is certainly not the first to use "Mary Cheney, Mary Cheney" as a title. Katha Pollitt (from The Nation) wrote a nice column with that title, right before the November 2004 presidential election. Katha didn't explicitly mention the reference, however, to "Mary Hartman, Mary Hartman" (I've wanted to work that show into a blog entry, and there you go). Sometimes things look so bleak that all you can do is laugh. Or cry. Or try to get rid of that embarassing waxy yellow buildup on your kitchen floor.

Interactions with other responsive agents lie at the core of all social exchange. During a social exchange with a partner, one fundamental variable that must be computed correctly is who gets credit for a shared outcome; this assignment is crucial for deciding on an optimal level of cooperation that avoids simple exploitation. We carried out an iterated, two-person economic exchange and made simultaneous hemodynamic measurements from each player's brain. These joint measurements revealed agent-specific responses in the social domain ("me" and "not me") arranged in a systematic spatial pattern along the cingulate cortex. This systematic response pattern did not depend on metrical aspects of the exchange, and it disappeared completely in the absence of a responding partner.

OK, so in this figure we have "me" and "not me" brain responses with a different spatial distribution from those seen in the "Mental as Anything" study by Mitchell et al. Granted, making judgments about people similar or dissimilar to one's self (Mitchell et al., 2006) is different from "ascribing agency" in an economic game (Tomlin et al., 2006).

The Mitchell et al. paper concludes thusly,

As such, prejudice may arise in part because perceivers assume that outgroup members’ mental states do not correspond to their own and, accordingly, mentalize in a non-self-referential way about the minds of people from different groups. Without a self-referential basis for mentalizing about outgroup members, perceivers may rely heavily on precomputed judgments—such as stereotypes—to make mental state inferences about very dissimilar others. This view suggests that a critical strategy for reducing prejudice may be to breach arbitrary boundaries based on social group membership by focusing instead on the shared similarity between oneself and outgroup members.

and here's the Tomlin et al. conclusion:

However, it is reasonably clear that cingulate and paracingulate cortices contribute to normal social cognition and adaptive decision-making. The results of this paper add the important possibility that many other variables in the social domain may be arranged in such a systematic fashion through the spatial domain, a phenotype that could be disturbed in afflictions where the capacity to distinguish "me" from "not me" is impaired.

Uh, yeah.

But let's go back to the experiment. I give the authors credit for developing the nifty "hyperscanning" methodology, which involves two subjects who interact with each other while their brains are scanned simulateously (in adjoining or distant magnets). The task ("the trust game") is illustrated below. Brain images are taken at the three critical "reveal" points below:An obvious confound is that the subject knows what he/she did, but not what the other person did. How did the researchers account for that? They did control experiments in separate groups of subjects.

One question deserves separate consideration: Did the reveal screens generate simple surprise or novelty responses along cingulate that were not related to the social element of the exchange? Although this reasonable interpretation is possible, the control experiments suggest otherwise. The response pattern along the cingulate disappeared in the control experiments where subjects received stimuli that were visually identical to those in the trust game and were composed of novel, reward-related information.

However, it's very surprising(!) that novelty and reward did not activate the cingulate in these control conditions, given the number of studies that have reported otherwise.

For the life of me, I can't figure out what we've learned from this article and why it's imporant. So I'll ask some other questions.

(1) Whose work forms the basis for the article?

These experiments have elicited not only brain responses in previously described theory-of-mind networks (27–29), but also have elicited formerly unreported activations along the cingulate cortex that correlate with the revelation of a social partner's decision (29). Although evoked during an economic exchange with another human, these cingulate activations did not modulate as a function of the fairness of the exchange, nor did they occur in exchanges with computer partners (28).

. . .

Given the previously reported activations in the anterior and posterior portions of the medial cingulate during a social exchange (28), a detailed analysis of the cingulate cortex in each pair of subjects was performed.

In working backward from outcomes to behavior or in strategic planning for future scenarios, one important issue is who gets the credit (and how much) for the eventual result. In the trust game, the first player has to decide how much money to invest, and the second player has to decide how much of the multiplied investment to give back. Tomlin et al. (p. 1047) have carried out a large-scale simultaneous brain imaging study and suggest that different regions of the cingulate cortex become active when what the "other" player has chosen to do is revealed, compared with situations when "I" have done the choosing.

About Me

Born in West Virginia in 1980, The Neurocritic embarked upon a roadtrip across America at the age of thirteen with his mother. She abandoned him when they reached San Francisco and The Neurocritic descended into a spiral of drug abuse and prostitution. At fifteen, The Neurocritic's psychiatrist encouraged him to start writing as a form of therapy.